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From: "shaohua.li at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/111764] New: Wrong code at -O3 on
 x86_64-linux-gnu since r11-5965-g04bff1bbfc1
Date: Tue, 10 Oct 2023 20:54:27 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: wrong-code
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111764

            Bug ID: 111764
           Summary: Wrong code at -O3 on x86_64-linux-gnu since
                    r11-5965-g04bff1bbfc1
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shaohua.li at inf dot ethz.ch
                CC: rguenth at gcc dot gnu.org
  Target Milestone: ---

gcc at -O3 produced the wrong code.

Bisected to r11-5965-g04bff1bbfc1

Compiler explorer: https://godbolt.org/z/7vaqadYfP

$ cat a.c
int printf(const char *, ...);
char a;
short b, c;
static short *d =3D &b, *e =3D &b;
short(f)(short g, short h) { return g * h; }
int main() {
  *e =3D 2;
  a =3D 1;
  for (; a <=3D 9; a++) {
    short *i =3D &c;
    *i =3D *d =3D f(*e, *e);
  }
  printf("%d\n", c);
}
$
$ gcc -O0 a.c && ./a.out
0
$ gcc -O3 a.c && ./a.out
4
%=